The aim is to understand the chemical composition of coals, with a long-range goal of reducing the environmental health hazards they present. EPR measurements of coal and separated macerals were made at W-band. The greatly improved spectral resolution is providing new data on the nature of radicals found in coal, and on the distribution of organic sulfur. Quantitative methods are now being developed in order to determine the concentration of sulfur radical species in samples. This is a continuing project; new results were obtained through 1993.